Influence of different infracardial positions of central venous catheters in hemodynamic monitoring using the transpulmonal thermodilution method

Hemodynamic measurements are often conducted by the transpulmonary thermodilution (TPTD)-based PiCCO^®-system. This requires a central-venous (CVC) and a thermistor-tipped arterial catheter, usually placed in the femoral artery. In certain clinical situations, CVC devices have to be placed in the inferior vena cava. However, little is known about the influence of different CVC positions (i.e. ipsi- vs. contra-lateral to the arterial catheter) on the accuracy of the TPTD measurement results. In this prospective observational study surgical intensive care unit patients who had been inserted with CVCs either into the superior (CVC_VCS) or the inferior vena cava (CVC_inf) in addition to an arterial PiCCO^®-catheter, were enrolled. Patients were then divided into two groups: Group I was provided with a CVC in the contralateral (CVC_contra) and Group II in the ipsilateral (CVC_ipsi) inferior vena cava. Thermodilution via injection of ice-cold saline was then performed via CVC_sup and CVC_inf. Bland–Altman analysis for cardiac index (CI), extra-vascular lung water index (EVLWI) and global end-diastolic volume index (GEDVI) were employed. Additional correction formulas for femorally assed parameters were determined. In a total of 28 patients, bias (limits of agreement) for measurements of CI in CVC_contra was found to be +0.2 (−0.4; +0.9) and +0.3 (−0.4; +1.0) L/min/m² in CVC_ipsi. GEDVI showed a bias of +274.8 (−47.3; +596.9) mL/m² in CVC_contra and +274.7 (−100.7; +650.1) mL/m² in CVC_ipsi. The mean EVLWI were 9.4 ± 4.3 mL/kg for EVLWI_VCS and 10.7 ± 5.2 mL/kg for EVLWI_inf. The LoA yielded at −3.4 and +6.1 mL/kg with a bias of +1.3 mL/kg. Percentage errors revealed clinically acceptable limits for CI and GEDVI, but not for EVLWI. Using TPTD via an infracardial central vein, measurements of CI showed high accuracy and precision while GEDVI measurements were precise with a lower accuracy, irrespective of the position of the infracardial CVC.